At a meeting: "The Japanese word for dress shirt, wai shatsu, comes from the English for 'white shirt,' which gives you an idea of the range of colors worn at work," says Dan Rosen, professor at Tokyo's Chuo Law School, who recommends basic black suits. In 2005, the government launched a Cool Biz initiative meant to lower AC costs by encouraging lighter work attire; it's been met with fierce resistance by the jacket-and-tie-loving Japanese working class.

On the street: For Tokyo youth, nothing's too studied or over-the-top, so the laissez-faire American norm is seen as slovenly. Women should wear heels, makeup, and a dose of frills, and men must be clean shaven and must spend time on their hair.

At a party: Agnès B. and Louis Vuitton are the easiest icebreakers, since the Japanese love labelsalong with the stylish shapes by local designers like Yohji Yamamoto. No sweat suits, please!

P.S. Planning to shop in Japan? Note that Japanese sizes run significantly smaller than those in the States. If you wear a medium in the United States, a Japanese XL might be a squeeze.